Get Fitter in Only 5 Minutes With the AI-Enabled Carol Bike

I was prepared to mock the Carol Bike relentlessly. The reason you buy this insanely expensive exercise bike is to access Carol Bike’s signature reduced-exertion high-intensity interval training (REHIT) workouts. This is a signature five-minute workout that consists of two 20-second sprints, bracketed by a warmup, rest, and cooldown period.
You can only do REHIT workouts on a Carol Bike because the bike applies and removes resistance instantaneously, and Carol’s AI-enabled algorithms are able to personalize the exact level of resistance you need for each interval. The company makes all sorts of hyperbolic claims about this workout—for example, saying that five minutes on the bike is equivalent to a 45-minute run.
The day I received my tester, I texted my cyclist friends, to uproarious laughter all around. “A stationary? For five minutes a day????” my BFF texted back. It is to my grave disappointment that I must report that after two weeks of riding the Carol, I … love it. Although I have yet to see improvement on my metrics—Carol notes that it can take up to eight weeks—I already feel stronger. You incorporate REHIT into your existing routine, instead of replacing it.
I’ve tested other exercise bikes before and there are a few significant differences with the Carol Bike. First, the footprint is tiny—a mere 45.5 x 22 inches. This is much smaller than the NordicTrack, which is 55 inches long (the NordicTrack is more than $1,000 cheaper). It’s small enough that I wasn’t bothered (too much) by placing it off to the side in my kid’s playroom.
The screen also isn’t proprietary to the bike. On my tester, the assembly company simply unboxed a Lenovo Tab P11 and put it on a magnetic rack where the screen would go. As far as Android tablets go, it’s just OK. But as an exercise bike’s touchscreen, it’s great!
The OLED screen is bright and sharp, and the touchscreen responsive. I find Android OS to be, uh, quirky? But if all you’re doing is running a simple Bluetooth-connected exercise program, it’s more than fine.
Using a regular Android tablet also makes it possible to switch between Carol Bike and other fitness apps like Peloton, or to, say, switch from Carol Bike’s program to Netflix (although the company did take the precaution of blocking other fitness apps on my tester).
The transmission is also instantaneous and remarkably quiet—no loud chunk-chunk-chunk as the machine ratchets the tension up or down. I have never ridden an exercise bike that can jack up the resistance so quickly or so silently.
As far as the rest of the specs go, it’s a pretty basic exercise gym bike. It can accommodate riders from 4’7″ to 6’7″ and up to 330 pounds. It can use standard power outlets in either the US or Europe, and a basic plug in my kids’ playroom was adequate. It didn’t feel unstable or at all rickety to ride, even without a bike mat to put it on. The seat is big, cushy, and comfortable.
Accessing Carol’s workouts requires a $20/month subscription. There are 22 workouts, so you can choose between the five-minute REHIT rides, Fat Burn, Free & Custom, and Fitness Tests, like checking your VO2 Max and testing your Functional Threshold Power (FTP), which measures how hard you can ride for an hour without throwing up and dying.
Before you can start riding, you do three preliminary ramp-up tests to calibrate the bike. It’s a measure of how little I thought of this whole program that I accidentally did all three calibration rides on the same day (you’re supposed to do them over a week).
While the Carol Bike does measure traditional metrics like FTP, it also has its own proprietary metric, the Fitness Score, which is based on your performance during and recovery from an anaerobic sprint. It’s worth noting here that I can generally tell which demographic a fitness machine is aimed for by looking at the leaderboard. I’m amazingly fit compared to Fitbit and Amazfit users, and average compared to Garmin’s; I’m only in the 30th percentile of Carol Bike’s users in my gender and age group, which was shocking. People who use the Carol Bike are very, very fit.
Once you select a workout, you pick your music type. Don’t worry too much about it, because it’s all bad. Once it starts, there are no entertaining instructors or videos of Norway to distract you from the pain of the anaerobic sprint—just breathing instructions, little written mantras, and a timeline at the bottom to tell you when to sprint and when to rest. If you’re easily distracted, the whole screen turns bright red to tell you when it’s time to lay down the hammer.
There are five different hand positions on the bike, and trust me when I tell you that I used all of them, especially during the insane Fat Burn workouts. It’s meant to trigger a huge calorie burn with 60 (!!!) eight-second all-out sprints with a 12-second recovery time, for 17 to 25 minutes. It’s really hard and you need an extremely responsive exercise bike to do it! This is when I stopped making fun of the Carol Bike in my head—when the program started warning me to skip some sprints before I keeled over.
Carol Bike notes that REHIT is scientifically backed. Technically, it is. There is one small-scale study with 20 participants at Western Colorado University that shows that, while calorie burn during the ride is lower compared to regular treadmill workouts, the excess post-exercise energy consumption (EPOC) continues throughout the day.
The Carol Bike is not for dilettantes. It is for people who are kind of psychotic about working out and are way too bummed if life circumstances force them to skip a day. With a Carol Bike in my house, it doesn’t matter that I got off work at 4 pm and made plans to meet a friend at 5 pm. I still can run upstairs, throw on some leggings, strap the heart rate monitor on my chest, do a REHIT workout, and run out the door 20 minutes later. There’s even toe cages, so you don’t have to change your shoes into clip-ins and can just hop on in your Vans.
The bike’s exercise program talks you through the workouts, and one mantra that stuck in my mind was the bike reassuring me, “Now you can work out because you want to, and not because you have to.” I found this reminder to be way too helpful. Now I don’t have to worry about getting a run in and getting in my lifting/climbing/hiking with my dogs and kids. I can do both! I can do it all! There’s a minimum level of exertion that I need every day to be a decent human being, and the Carol Bike makes it possible to squeeze it all in.
After a mere two weeks on the Carol, I’m starting to notice that I’m getting stronger. The Amazfit T-Rex 3 that I’m currently testing has noted in my runs that my performance is improving. I smoked my friends on a recent hike with 2,100 feet of elevation gain. (Let them please not read this! However, it’s true and I noticed.) More isn’t always better. Carol Bike, I’ll eat my words. And my texts.